What microscopic structures are in the small intestine that absorb materials?

villi/microvilli

Explanation:

the villi absorb nutrients in your small intestine, microvilli increase surface area so nutrients are taken in more quickly

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands

the endomembrane system i think